In kindergarten, you learned to put things in your cubby. After playtime, everything had to go back to its proper place. When you got older, you got your own desk, and then, after a few more years, upgraded to a locker.
Now that you're a man, you have a lot more “cubbies” all around your apartment, but you should still use what you learned all those years ago in kindergarten. Everything has its place (or should). However, sometimes things can get out of hand and suddenly… clutter! Clutter everywhere!
One way to lessen the clutter around your place is to stop it before it starts. Really think about what comes into your home. For instance, don't let mail and magazines pile up and start spreading out to different surfaces and rooms.
Create a designated spot, such as the end of the kitchen counter, where everything goes when you get home. Once you put away your keys, groceries, and so forth, all you should be left with is maybe some mail and paperwork.
Regardless of what's left, your goal before you go to bed is to make sure this area is completely clear.
For more information on setting up a “landing strip”, check out this video from Apartment Therapy:
Don't let your kindergarten-self be more disciplined than you!